1. Technical Field
This invention relates to fuel tanks and, more particularly, to fuel tanks made of plastic material.
2. Discussion
The desire for a fuel efficient and durable vehicle that satisfies the requirements of today's sophisticated consumer has placed difficult demands on modern fuel tank design. Plastic fuel tanks are gaining notoriety for meeting these demands. One such demand is the desire to reduce overall vehicle mass. The use of a lightweight plastic fuel tank, rather than a conventional metal fuel tank, helps achieve the goal of reduced vehicle mass.
Another demand on today's vehicle design is roominess in the passenger compartment. Increasing the roominess of the passenger compartment, without increasing the overall size of the vehicle, results in a cramped engine compartment and under carriage. This cramping of the under carriage conflicts with the consumer's desire to have a larger gas tank and thereby have longer range between fill-ups. To accommodate an optimal design of maximum tank volume in a minimum of available under carriage space, the fuel tank design required for a given vehicle may be one of irregular shape. Conventional metal gas tanks, generally being produced by a stamping operation, typically cannot easily meet these irregular shape requirements.
Another common characteristic of a cramped under carriage is the gas tank being in close proximity to an exhaust system. Conventional metal gas tank walls do not provide insulation from these types of local heat sources.
Safety and crash worthiness is also an important factor in the design of modern vehicles. Conventional metal gas tanks usually consist of two diametrically opposed stamped shells that attach to one another. This attachment results in a seam that extends around the circumference of the gas tank. A second seam may also be created where a filler neck attaches to the gas tank wall. These seams are potential sources of failure.
Plastic fuel tanks are known in the patent literature as, for example, in U.S. Pat. No. 4,660,738 to Ives; U.S. Pat. No. 4,625,980 to Lyzohub; U.S. Pat. No. 4,602,722 to Ives; U.S. Pat. No. 4,518,091 to Scheurenbrand et. al.; U.S. Pat. No. 4,482,075 to Stotz et. al.; U.S. Pat. No. 4,453,564 to Bergesio; U.S. Pat. No. 4,416,303 to Scheurenbrand; U.S. Pat. No. 3,595,422 to Durrett, Jr.: U.S. Pat. No. 3,552,599 to Redding; and U.S. Pat. No. 3,470,907 to Shockey. However, while each of these designs may have purported advantages over their metal counterparts, substantial improvements to the art remain to be made.